Buy a SIM

I wanted to buy a SIM card for an Android terminal and I went to an AT&T store in Little Rock (AR) - the store at  Park Avenue Shopping Center

The store was almost empty, I was put in a waiting list and I started to wait. My name was at the 8 place.

After an HOUR my name disappeared from the list !  I did ask why and they told me I was called and I didn't answer.
Useless to say nobody called me or even approached me. Possible in an hour nobody saw me seat down at one of the table waiting ?

I was told to come the day after !  How rude !

I was not even able to ASK or tell what I wanted and why I was there !

Useless to say I will NEVER put a foot in that shop but since NOBODY THERE even bothered to ask what I needed, I'm asking here, is possible to buy just a SIM nano with NO contract since it has to be activated by a third party ? (a company that has already a contract with AT&T).
The reason was to speed up some tests I have to do with the terminal for a customer.
I am EXTREMELY disappointed by the total lack of professionality and simple human decency at that store !

I'm considering to recommend to that company to chose another provider.